在bootstrap 4中堆叠的可折叠导航栏

Question

我想创建一个可折叠的navbar.一切正常,但nav物品不会像它应该的那样堆叠在一起.它们彼此水平相邻.

码:

<nav class="navbar navbar-light bg-faded" role="navigation">
    <button class="navbar-toggler hidden-sm-up" type="button" data-toggle="collapse" data-target="#collapsing-navbar">
        &#9776;
    </button>

    <div class="collapse navbar-toggleable-xs" id="collapsing-navbar">   
        <a class="navbar-brand" href="/">Logo</a>

        <ul class="nav navbar-nav">
            <li class="nav-item">
                <a href="/messages" class="nav-link">Messages</a>
            </li>

            <li class="nav-item">
                <a href="/logout" class="nav-link">Logout</a>
            </li>
        </ul>
    </div>
</nav>

截图:

Answer 1

Bootstrap 4 Alpha 6(内置alpha 6版本堆叠菜单 - 无需使用额外的CSS):

<nav class="navbar navbar-toggleable-md navbar-light bg-faded">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="#">Navbar</a>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="text" placeholder="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

CODEPEN

Answer 2

看起来这个CSS覆盖更容易完成:

@media(max-width:768px) {
    .navbar .navbar-nav>.nav-item {
        float: none;
        margin-left: .1rem;
    }
    .navbar .navbar-nav {
        float:none !important;
    }
    .navbar .collapse.in, .navbar .collapsing  {
        clear:both;
    }
}

http://codeply.com/go/Ar1H2G4JVH

UPDATE

从BS4 alpha 6开始,不再需要额外的CSS.导航栏标记已更改. http://www.codeply.com/go/0OMz6nfPLr